Answer:
The Zimmermann Telegram (or Zimmermann Note or Zimmerman Cable) was a secret diplomatic communication issued from the German Foreign Office in January 1917 that proposed a military alliance between Germany and Mexico.
Step-by-step explanation:
On January 16, 1917, British code breakers intercepted an encrypted message from Zimmermann intended for Heinrich von Eckardt, the German ambassador to Mexico. The British cryptographic office known as “Room 40” decoded the Zimmermann Telegram and handed it over to the United States in late-February 1917.